Nowadays, there are known a variety of methods for research of influence of seismic waves or electromagnetic field impulses upon a seabed, a subsequent registration of changes of near-bottom strata parameters, and analysis of thus obtained data for a detection of existing anomalies and a determination of their nature. These methods are widely employed for survey of seabed hydrocarbons deposits. The surveys are executed with the help of various research equipment complexes (e.g., taught in RU2236028, 2004; SU1122998, 1984; SU1798666, 1996; SU1434385, 1988; U.S. Pat. No. 4,298,840, 1981; U.S. Pat. No. 4,617,518, 1986, RU2324956, 2007). Recently, a trend in marine geophysics has been developed for the use of bottom stations (also known as bottom systems), herein further referred to as ‘BS’, for gathering information on seabed strata, including both self-emerging BS, and BS without self-emerging capacity.
The type and configuration of BSs used are determined by survey specifics, as well as by the seabed relief, in particular, by the depths in the marine survey zone. At the same time, for obtaining a reliable prognosis, it's necessary to keep a range of conditions, in particular, deployment of the BSs at a certain distance from each other and obtaining accurate information on the locations of BSs on the seabed.
In this connection, the equipment, ensuring the placement of BS on the seabed and their return on the ship's board, becomes particularly important.
For providing a fixed placement of seismic BSs on the seabed, a company named Sea Bird (see D. E. LEVASHOV Modern ships and ship equipment for fishing researches, VNIRO, 2010 p. 197-200) used a specifically equipped underwater remotely operated vehicle (ROV). Such a method ensures high accuracy of the BSs placement; however, it is extremely unproductive and very expensive. Moreover, it requires a ship of significant dimensions and allows for working only with relatively compact seismic stations.
Typically, at the majority of ships used for placement of the BSs, various trawl and auxiliary winches, as well as cargo cranes are employed (D. E. LEVASHOV Modern ships and ship equipment for fishing researches, VNIRO, 2010 p. 197-271). However this equipment is bulky, requires a large space, and doesn't provide for a precise placement of the BSs.
For increasing the efficiency of BS operations, especial cargo-grasping devices were designed (e.g. RU 2034767, 1995; RU 2025427, 1994), comprising a case provided with rotational jaws and a mechanism for operating thereof. However, such devices have the following deficiencies: they are slow-working, in particular, in tossing conditions; and it's difficult to adjust the rotational jaws at clamp places of the cargo.
For deployment of electrical survey BSs, the instant inventors have developed a manipulator device (RU90006, 2009), comprising a frame, jaws hingedly coupled with the frame, a drive for closing the jaws, and a mechanism for suspension of the frame and coupling thereof to the manipulator's boom, also supplied with a damper, allowing for rotation of the frame relative to the boom in the vertical plane of the manipulator's movement and in the plane of rotation of the frame relative to the boom. The manipulator device ensured a deployment of BSs with a complicated design, but it wasn't sufficiently efficient for mass deployments.
There is known a patent application publication US 2011/0051550 A1, teaching an equipment complex, wherein a number of seismic stations, each including two connection links, are placed on the seabed with the help of connecting elements made of a cable, rope, or halyard, and having, at their ends, connecting parts of a spring hook (carabine) type. The distance between seismic receivers on the sea bottom is determined by the length of the connecting element. During deployment of the seismic BSs, they are placed on a frame assembly and are preliminary connected with freely coiled connecting elements. Such complex and deployment system ensure a sufficiently accurate placement (2% of the sea depth) of the BSs on the sea bottom for works at depths not exceeding 50 m. However, it is not satisfactory at greater sea depths, wherein a ratio of the distance between the BSs and the connecting element length decreases nonlinearly. Moreover, in this complex's configuration, at lifting BSs with two fastening points, difficulties arise due to a tension on the connecting elements.
The nearest to the claimed solution is U.S. Pat. No. 7,649,803, teaching an equipment complex mounted on a special ship, which complex ensures a deployment of a number of seismic BSs on the seabed, and their lifting onto the ship's board after the completion of sea works. The complex comprises a line located on a winch; wherein the line includes BS fastening knots of a split ring type, connected with one another by load-bearing units, while the length of the line ensures placement of the seismic BSs along the entire survey profile. The load-bearing units can be made of a non-stretched halyard, rope, or isolated cable, having negative floatation.
The aforementioned complex is highly technologically effective at deploying and lifting BSs, and ensures uniformity of their placement on the seabed. However, it's employable only on specialized ships and is destined only for works with a certain type of seismic stations.